<title>Design and fabrication of Smart Wing wind tunnel model and SMA control surfaces</title>

Abstract

To verify the predicted benefits of the smart wing concept, two 16 percent scale wind tunnel models, one conventional and the other incorporating smart wing design features, were designed, fabricated and twice tested at NASA Langley's 16 ft Transonic Dynamic Tunnel, in two series of tests, conducted in May 1996 and June 1998, respectively. A key objective of the Smart Wing Phase 1 program was not only to construct wind tunnel models that could be used to validate the predicted benefits of using smart materials, but also to identify and reduce the risks involved in eventually integrating smart materials into an actual flight vehicle. Among the challenges encountered in developing the wind tunnel model were the attachment of the shape memory alloy (SMA) control surfaces to the wing box, integration of the SMA torque tube in the wing structure, installation of the instrumentation, and development of fail safe control mechanisms to protect the model and the tunnel in the event of failure of the smart systems. In this paper, design and fabrication details of the two Smart Wing Phase 1 wind tunnel models are presented. Among the topics covered are 1) model design requirements, model design and static testing; 2) manufacturing techniques with particular emphasis on the improvement in the design and fabrication of the SMA control surfaces from the first to the second test; 3) system integration; and 4) post-test analysis and planned improvement. Lessons learned from the Phase 1 effort are discussed along with plans for the Smart Wing Phase 2 program.